Rotary mixers of the type involved with this invention generally include a body forming an internal mixing chamber within which one or more rotors operate. The rotors are mounted on axial shafts which extend through the body at each end thereof for external journaling. The materials being mixed may produce a large amount of very fine dust in the chamber. In order to prevent this dust from escaping from the chamber, through the rotor shaft openings in the body, an annular sealing assembly is constructed in the shaft openings.
Conventionally the sealing assembly consists of a gland ring, a backing ring, and a yoke. The yoke is attached to the body by means which provide a fulcrum for the lever action of the yoke. One end of the yoke is attached to the backing ring at points approximately 180.degree. apart, while the other end is operatively connected to an hydraulic cylinder which when actuated pivots the yoke on its fulcrum. The lever action of the yoke transmits the force of the cylinder to the backing ring, which in turn applies the force to the gland ring. The gland ring engages a surface of the rotor resulting in a seal which is under continuous pressure from the hydraulic cylinder. When it is desired to clean the sealing assembly, this pressure may be released thereby freeing the gland ring to allow the mixing chamber to be purged.
This type of sealing assembly is adequate for small mixers, however as the mixers become larger the yoke becomes extremely cumbersome and difficult to construct. The sealing gland rings are also larger and therefore require additional points at which the sealing force should be applied. Therefore the indirect application of the sealing force through the yoke is no longer effective. It is the object of this invention to provide an apparatus for applying the sealing force directly to the gland ring.